Gas-fractionating installation



Nov. 27, 1956 c, JONKERS ETAL 2,771,751

GAS-FRACTIONATING INSTALLATION I Filed July 15, 1954 2 Sheets-Sheet 1 .9 /0 I7 IS INVENTORS CORNELIUS OTTO JONKERS OHANNES VAN R STER %fl/% AQENT Nov. 27, 1956 c. o. JONKERS ETAL 2,771,751

GAS-FRACTIONATING INSTALLATION Filed July 15, 1954 Sheets-Sheet 2 ////fl CORNELIUS OTTO JONKERS JACOB WILLEM LAURENS KOHLEF AUGUST ALBERT LIEBE JOHANNES VAN DER TER AGENT GAS-.FRACTIONATIING INSTALLATION Cornelius ()tto Junkers, Jacob Willem Laurens Kohler,

August Albert Liehe, and Johannes van der Ster, Eindhoven, Netherlands, assignors to Hartford National Bank and Trust Company, Hartford, Conn, as trustee Application July :15, 1%54, erial No. 443,582 Claims priority, application Netherlands July 24, 1953 5 Claims. (Cl. 62-122) This invention relates to gas fractionating installations comprising a rectifying column in which the vaporous fraction of the lowest boiling points which rises from the column is condensed by means of a cold-gas refrigerator.

In such installations it is possible to form the column as .a so-called single column, this in contra distinction with the conventional installations, in which it is com- .monly necessary to form the column in the shape of a SO-Cfiillfid double column in order to obtain a product of the desired purity. Consequently, it is advantageous to provide a gas-fractionating installation with a cold-gas refrigerator. The term cold-gas refrigerator is to be understood to mean a so-called refrigerator operating on the reversed hot-gas motor principle. As is well-known, such machines may be made of different constructions, for example as a displacer machine, as a double operating machine, as a machine with the cylinders arranged in V-form, or as a machine of which the working space is combined with that of a hot-gas motor.

if the gas-fractionating installation comprises a coldgas refrigerator, the fraction of the lowest boiling point which escapes from the rectifying column may be condensed by the refrigerator. The condensate may be tapped from the refrigerator, but part of the condensate will have to be supplied again as a washing liquid to the column and another part may be discharged from the installation. This could be eflected by providing the refrigerator with a discharge channel comprising, for example, a cock. However, this construction appears to have the disadvantage that the cock is required to be displaced when the cold output of the refrigerator is varied, so that the installation needs continuous supervision.

The object of the invention is to provide an installation of a construction such that continuous supervision is not necessary or at least necessary to a smaller extent only.

According to the invention, provision is made of means by which the condensate is divided into at least two portions, one portion serving as a washing liquid [for the column and another portion being discharged from the installation in such manner that the ratio between the said portions is substantially independent of the cold output of the refrigerator.

The invention may be realised in different ways. In one embodiment of the invention in which the con-densate is collected in a chute, the means of dividing the condensate are constituted by the chute, which comprises an outlet for each amount of condensate, and a partition which is provided in the chute between the two outlets.

In a further embodiment of the invention, the partition is adapted to be displaced for the adjustment of the desired ratio between the condensate to be discharged and the condensate to be supplied back to the column, which ratio is indicated as the so-called reflex ratio.

2,771,751 Patented Nov. 27, 1956 In another embodiment of the invention, the chute is annular 'in shape and comprises outlet apertures.

An embodiment which is simple instructural respect is obtained if the cold-gas refrigerator comprises an annuiar chute and a partition which is adapted to be displaced is provided therein between two apertures, while "a fixed partition is provided -in that part orthose parts of the chute which is or are located on the other side of each aperture.

in another embodiment of the invention, the means of dividing the condensate are constituted by a container comprising a supply channel 'tor'the condensate and at least two discharge channels extending in the vertical direction, heat being supplied to the condensate in the discharge channels, resulting in a vapour-bubble pumping action-in each channel.

Since a vapour bubble pump has a comparatively low output, the heat required for evaporating the condensate may best be extracted from parts of the installation which are at a temperature higher than of the liquid as a result of the process performed in the installation. It is thus possible to utilize the cold extracted from the liquid to be evaporated.

In one embodiment of the invention, the thermal loss ,of the installation through the insulation is utilised at least in part for heating the liquid in the discharge channels.

In another embodiment of the invention, a medium to be cooled is used for heating the liquid in the dischargechannels. The medium to be cooled may be, for example, the gas-mixture which is to be fractionated.

Since in this case also it maybe desirable for the reflux ratio to be adjustable, in a further embodiment of the invention each supply channel comprises, in addition, an electric heating element which permits of supplying an additional amount of heat to the condensate in these channels.

'In one embodiment of the invention preferably, at least one discharge channel is connected to the cold-gas refrigerator, so that the vapour produced during the heating of the condensate may be supplied to the coldgas refrigerator for renewed condensation.

:In one advantageous embodiment of the invention, the vapour-bubble pumps are provided in the insulating envelope of the column.

In order that the invention may be readily carried into effect, it will now be described with reference to the accompanying drawings, given by way of example, in which:

'Figs. 1 and 2 show a coldega-s refrigerator comprising means for dividing the condensate produced by the refrigerator into two portions. Fig. 2 is a cross-sectional view taken along the line lIfI l of Fig. 1.

Fig. -3 shows another embodiment of a chute which may be used for dividing the condensate produced by the refrigerator, and

Figs. 4 and 5 shows a third embodiment of a chute.

Fig. 6 shows a gas-fractionating installation in which the means of dividing the condensate are constituted by two vapour-bubble pumps.

The. cold-gas refrigerator shown in Fig. 1 comprises a cylinder 1, in which a displacer 2 and a piston 3 are adapted to reciprocate. The displacer 2 is coupled by means of a driving-rod system 4 to a crank 5 of a crankshaft 6, the piston 3 being coupled by means of driving rods 7 to crank of the same crank-shaft 5. The cranks 8 on the one hand and the crank 6 on the other hand are at an angle with one another so that the displacer and the piston reciprocate with a constant phase difference. This results in. substantially harmonic variation of the volume of a space 9 above the displacer ll. This.

space communicates by means of a freezer 10, a generator 11 and a cooler 12 with a space 13 which is located between the displacer and the piston and of which the volume likewise varies substantially harmonically. The space 9 is frequently called the freezing space, the space 13 frequently being indicated as the cooled space. The head of the cold-gas refrigerator is surrounded by a wall 14 having heat-insulating properties, which encloses a space 15 in which a medium may be cooled. The space 15 exhibits an inlet aperture 16 for the medium to be cooled, for example a vapour, the condensate produced by cooling being collected in an annular conduit 17. The conduit 17 comprises two discharge channels 18 and 19. The medium is condensed on fins 20 provided on the side-wall of the head, the condensation in this embodiment being affected throughout the periphery of the head. A fixed partition 21 and a movable partition 22 are arranged in the annular conduit 17. Due to the presence of the said partitions, the conduit 17 is divided into two parts 23 and 24, each having a discharge channel 18, 19 respectively in its own. The size of each of the said parts determines the amount of condensate that can be discharged through the channels. The channel 18 is connected, for example, to a gas-fractionating column in which the condenstate serves as a washing liquid. The medium flowing through channel 19 may be carried off as the product which is desired.

When the cold production of the refrigerator decreases, the amount of condensate decreases, but the ratio between the amounts of condensate collected in each part of the annular conduit remains constant, so that in this embodiment the ratio between the parts into which the condensate is divided is independent of the cold production of the refrigerator. Should it be desirable to slightly vary the division, the partition 22 may be displaced by turning aknob 25, which is connected to the said partition by means of a rod 26.

Fig. 3 is a plan view on a chute 30 for collecting the condensate produced by a cold-gas refrigerator. The chute 30, which may alternatively be formed as a channel, comprises two outlets 31 and 32 and a partition 33 provided between them.

Due to the presence of the outlets 31 and 32, the liquid flowing through the chute 30 is divided into two parts. If the cold production increases, the level of the liquid in the chute 30 rises, but the ratio between the discharged amounts of condensate remains constant. If desired, the ratio may be varied by displacing the partition 33.

Fig. 4 is an elevation view of another embodiment of the invention and Fig. is a plan view thereon. The means in this embodiment comprises a chute 40, from which the condensate flows down as a kind of waterfall. The condensate is collected in a chute 41, which is divided by means of a partition 42 into two parts, viz. the parts 43 and 44. If the cold production of the refrigerator varies, the level of the liquid in the chute 40 will vary, but the ratio between the amounts divided by the partition remains unchanged. The ratio between the amounts discharged may be varied, if desired, by displacing the partition to the left or to the right, which may be effected by means of a rod 45.

The gas-fractionating installation shown in Fig. 6 is constituted by a column 50 comprising a boiling vessel 51 which contains a heat-exchanger 52. The heat-exchanger 52 comprises a supply channel 53 connected to a compressor 54, which channel includes a heat-exchanger 55. The compressor comprises a suction line 54 which is connected to the vessels 56 and 57 filled with chemicals, thus enabling the mixture of gases which is drawn in to be purified in the said vessels. The heat-exchanger 52 comprises a discharge line 58 which is connected to the column 50. The pressure of the compressor is so low that the resistance of the vessels 56 and 57 and that of the heat-exchangers 52 and 55 is overcome, but that the gas-mixture is nevertheless supplied at atmospheric or substantially atmospheric pressure to the column in which the gas-mixture is fractionated. The fraction having the lowest boiling point is supplied from the upper end of the column through a channel 59 to a cold-gas refrigerator 60, which causes the fraction to be condensed. Both the compressor 54 and the refrigerator 60 are driven by an electric motor 61. The condensate produced by the refrigerator is supplied through a channel 62 to a container 63 which comprises two rising pipes 64 and 65. The pipe 64 comprises a portion 71 which empties into the vapour channel' 59, and the pipe 65 comprises a portion 72 which also empties into the vapour channel 59. The container 63 and the rising pipes are provided in an insulating envelope 67 of the column in which a metal screen 66 is also provided. The rising pipes 64 and 65 are soldered to the metal screen 66. The latter is located in the insulating envelope at an area such that, without the heat-exchanging contact with the pipes 64, 65 it would have a temperature which exceeds the boiling point of the liquid in the said pipes. Thus, the screen is positioned in such a place in the insulating envelope 67 that its temperature is sufficiently higher than the temperature of the liquid nitrogen in the pipes 64 and 65. The aforesaid may be easily accomplished since the temperature from the outside of the insulated envelope or casing decreases steadily. If the pipes 64 and 65 are connected to the screen, the screen heat is applied to the pipes due to the difference in temperature between the surroundingenvelope and the screen. Due to this heat the nitrogen in the tubes will boil and a vapor pump will be formed. The rising pipes 64 and 65 furthermore each comprise an electric heating element 68, 69 respectively. The rising pipe 64 comprises a portion 73 extending in the downward direction and having a liquid lock 74, which portion forms an outlet outside the insulating wall, so that part of the condensate may be discharged throughthis channel. The pipe 65 empties, at the upper end, into the column and the condensate flow ing through this pipe may serve as a washing liquid in the column.

The column 50 and the boiling vessel 51 are separated by a partition 75 having a pipe 76, which extends as far as under the liquid level in the boiling vessel, and a pipe 77 having a resistance such that in the boiling vessel above the liquid there prevails a pressure sufiicient to carry off part of the vapour produced in the boiling vessel through a discharge channel 78'and the heat-exchanger 55.

The operation of the installation is the following. The gas-mixture to be fractionated, for example air, is drawn inby means of compressor 54 through the vessels 56 and 57, in which the air is liberated from water vapour and carbonic acid, and subsequently supplied through channel 53, heat-exchanger 55, heat-exchanger 52 and channel 58 to the column. In the heat-exchanger52 the gas-mixture is in heat-exchanging contact with the liquid therein, of the highest boiling point, which isthus evaporated. The fraction of the lowest boiling point produced in the column, for example nitrogen, flows through channel 59 to the cold-gas refrigerator and is thus condensed, the condensate flowing through channel 62 to container 63. Heat is supplied to the rising pipes 64 and 65 by means of the metallic screen 66, so that a vapour-bubble pumping action occurs in the rising pipes and part of the condensate is supplied through channel .65 to the column and another part is discharged from the installation via channel 64, channel 73 and liquid lock 74. The vapour produced in the channels 64 and 65 may be supplied through the channels 71 and 72 to channel 59 for renewed condensation by the cold-gas refrigerator. In the construction shown, the amount of heat supplied to each rising pipe is the same. If the installation comprises a plurality of concentric insulating screens, it would be possible to supply each rising pipe with an amount of heat of its own, so that the vapour-bubble pumping action could be different for each pipe. If desired, the division in the above-mentioned installation may be varied with the use of the heating elements 68 and 69. In this embodiment also the division of the liquid produced by the cold-gas refrigerator is independent of the cold production. A portion of the fraction of the highest boiling point contained in boiling vessel 51, for example oxygen, may be discharged therefrom in the vaporous state through channel 78. It would alternatively be possible to obtain the vapour-bubble pumping action by bringing the liquid in heat-exchanging contact with a medium to be cooled. This could be effected, for example, by soldering the pipes 64 and 65 to channel 58 for the gas-mixture to be fractionated. This will be advantageous more particularly if the gas-mixture to be fractionated is supplied to the column at atmospheric pressure, since in this case it is commonly desirable that the medium should be cooled further during its flow through the channel 58, which may be effected by means of the liquid in the pipes 64 and 65.

If the channel portion 73 is of sufficient length, the compressor 54 may be dispensed with, the difference in pressure obtained as a result of the channel and the liquid lock then being sufficient to draw in the gas-mixture through the vessels 56, 57 and the heat-exchangers 55, 52.

In the construction above described it is possible to place the cold-gas refrigerator on the same base with the column, while the point at which the liquid fraction of the lowest boiling point is discharged is at a high level, so that it is not necessary for the operating staff to tap the liquid from the cold-gas refrigerator placed at a low level.

What is claimed is:

l. A gas fractionating installation of the type employed with a cold-gas refrigerator comprising a rectifying column in which the vaporous fraction of the lowest boiling point of the gaseous mixture is condensed by means of said cold-gas refrigerator, means dividing said condensate into at least two portions, one portion serving as a washing liquid for said column and means discharging the other portion from said installation, the ratio between said portions being substantially independent of the cold production of said refrigerator, an insulated housing mounting said rectifying column, a container in said housing, a supply channel for furnishing condensate to said installation, at least two discharge conduits extending in a substantially vertical direction in said housing, and means for supplying heat to the condensate in said discharge conduits whereby a vapor-bubble pumping action occurs in each of said conduits.

2. A gas-fractionating installation as claimed in claim 1 wherein the thermal loss of the installation through said insulating housing is at least partly utilized for heating the fluid in said discharge conduits.

3. A gas-fractionating installation as set forth in claim 1 wherein said medium to be cooled is used for heating the fluid in said discharge conduits.

4. A gas-fractionating installation as set forth in claim 1 further comprising an electric heating element for supplying an additional amount of heat to the condensate present in said discharge conduits.

5. A gas-fractionating installation as set forth in claim 1 wherein at least one discharge channel is connected to said cold-gas refrigerator whereby the vapor produced during the heating of the condensate is supplied to said refrigerator for renewed condensation.

References Cited in the file of this patent UNITED STATES PATENTS 1,557,907 Van Nuys Oct. 20, 1925 1,607,323 Van Nuys Nov. 16, 1926 2,095,809 Gomonet Oct. 12, 1937 2,409,458 Van Nuys Oct. 15, 1946 2,417,279 Van Nuys Mar. 11, 1947 

